Defining and exploring properties in diagnostic systems

Abstract

Every model-based diagnostic approach relies on a representation of a real-world system, in this paper called believed system. The believed system is used along with the observations about the real-world system to generate a diagnostic problem to be solved. In this paper it is firstly argued that believed systems can differ from real-world systems in many different manners. As so, properties of believed systems, diagnostic problems and diagnostic results are introduced. Then, a series of relations between these properties are proved. The importance of such relations, sometimes seen as intuitive, is that they are necessary to formally prove the accordance between the real-world system and the believed system; to formally prove that a believed system and a diagnostic problem will produce high-quality diagnostic results; or even to ease diagnostic algorithms, since for systems and problems with certain properties, different model-based diagnostic approaches produce the same diagnostic results. In order to introduce the referred properties and reasoning about them a framework of diagnosis based on the difference between the believed and the real systems is proposed.